import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BOARD)
GPIO.setup(3,GPIO.OUT)

def led_on():
    GPIO.output(3,False)

def led_off():
    GPIO.output(3,True)


for i in [1,2,3]:
    led_on()
    time.sleep(0.5)
    led_off()
    time.sleep(0.5)

GPIO.cleanup()
